Hypodermic syringe



April 1o, 1945. -{A/ALLnv y. 2,373,520

v mfPoDEms/IIGv SYRINGE r Filed Dec. 2, 1944 Lonen WALIJN Sworn/vbo@ Patented Apr. 10, 1945 UNITED sTAfrEsy PATENT. orties .N

mronnnivno `errantes n Loren Wallin, Wades'bo'ro, application December 2, 1944, serai No. .sacas- 2 claims. (o1. 112s-2.15)v

JThis invention relates toan improved syringe to which a hypodermic needle is adapted to be secured formaking intradermal injections and other injections into patients, whereby a definite vamount of the liquid can loe injected into the patient. AIt is an object of this invention to provide'a syringe constructedl so as .to remove the human element of error. With my syringe, properly opwhen the plunger is moved into the syringe, it

willr stop after a denite amount, say one-tenth of a cubic centimeter of the uid has been injected into the patient.

vrlhis type 'of a syringe is often used in "intraf dermal testing and medication. This includes tuberculin, Schick, Dick, and all of the numerous skin tests made vfor allergic conditions. 'There are other tests less often used. 'I'his'type of syringe is particularly adaptable ,for tests known as yf rroup testing. The' two 'types of group testing done routinely are Schick testing ,fordetermining the susceptibility .to diphtheria, and tuberculin testing to determine whether or not tuberculosis is pres,-

ent. 'These two tests are rperformed routinely` lby all health departments in the schools.v These, and all other -tests. depend for their value, upon absolute accuracy, and onetenth of a cubic centimeter is usually the dose. This permits of no variatio-n. Less than the 'prescribed dose might result in aialse negative, and more than the prescribed dose might result in a false` positive. The volume of this work is so great, and in addition, is so closely allied with other .phases of the public school health program, that this is usually assigned to the nurses to do. Whether they possess the degree of skill necessary to perform these very delicate tasks is often doubtful. When giving these tests by present methods, there are two things which might be carefully watched, one is the position of the needle in the skin, the other the position `of the plunger in the barrel of the syringe, 'and the very fine graduations on the barrel of the syringe. If the needle penetrates too deeply, the agent will be deposited subcutaneously and be rapidly absorbed, and the value as far as determining whether or not there is a following reaction is lost.V In lgivin-g undivided attention to the movement of the plunger within -the barrel, this sometimes happens.Y If, on the other'hand, too close attention is given to the lposition of the needle, the exact amount or onetenth of a cubic lcentin'ieter may, and'A probably will not |loe given. l

With my improved syringe, the dose is automatically controlled with' the entire attention of the attendant or operator being given to keeping the needle the 'properpositionr With the old type of syringe, the-'plunger is moderately easily movable lin the syringe barrel, and in giving tests, say Awhere one-tenth'of a oulbic ycentimeter is to be given tov each patient, it is necessary that the operator vnote exactly the reading on the barrel or the plunger of thesyringe before the needle is inserted into the patient, and 'also to stop the plunger at a definite point 'on 'thefgraduations so as to give exactly the one-tenth of a cubic centimeter or other `dosage which is required. p' By means kof my improved syringe, the operator merely turns the plunger a partial revolutie-nto cause the detent to ride out of the depression'in which it has stopped, and after the plunger has been forced intov the barrel, a predetermined amount, the detent will drop into the next gradu ation or cavity and will automatically stop the inward movement of the plunger, and thus the exact dosage kwill be, given and the operator will rbe permitted to focus` his entire attention oir the position of the needle in' the skin of the patient. y

.Some of ythe objects of the invention having beenstated, other objects will appear' as the description proceeds, when taken in connection'w'ith the accompanying drawing, in which- Figure 1 is an elevation of my improvedsyringe; omitting the conventional hypoderrnic needle which is attached to the lower end thereof;

Figure 2 is an enlarged detail view of my improved plunger for a syringe;

Figure 3 is a cross sectional view on an enlarged scale and taken along the line 3-3 in Figure 1;

Figure 4 is a cross sectional View through the syringe and taken along the line 4-4 in Figure 3; Figure 5 is an elevation showingthe reverse side of the plunger from that that Shown in Figure 2.

Referring morel specifically lto the drawing,

the numeral Il! indicates the syringe barrel in which a pIunger is adapted to have sliding movement.` The lower end of the syringe has the conventional opening I3 for egress of the fluid from the syringe barrel through a suitable hypodermic needle (not shown) which is attached to the discharge end o-f the syringe. The syringe is graduated in any suitable manner, in the drawing it being shown as graduated in .1 c. c. graduations. The plunger is also shown as being graduated ln .1 c. c. graduations so as to deliver `1 c. c. of the fluid upon each inward movement of the plunger before it is stopped by the detent. It is to be understood that the plunger and the syringe .barrel can be graduated in Iany desired pattern to deliver less or more than .l c. c. for definite purposes.

The plunger barrel II] has secured around the upper end thereof a tubular member I4 which is usually metallic, having a liange I5 and another flange I 6, the flange I 6 being thinner and reversely bent inwardly as at I'I to provide a cavity into which a spring member I8 is adapted to be tted. This spring member I8 has a leg or detent portion I9 which extends across and resiliently engages the plunger II at all times. The plunger II has a ground smooth portion 20 on its lower end, serving as tight seal between the wall of the cavity of the syringe I0 and the plunger so the plunger will act as a pump when it is drawn upwardly to cause the liquid to flow into the barrel I0 of the syringe. The main portion, however, of the plunger I I has a plurality of graduations 2|, 23, 25, 2l and 29 in the form of cavities on one portion thereoi` which extend approximately 90 degrees around the periphery of the plunger and it also has a plurality of graduations in the form of cavities 22, 24, 26, 28 and 3D, which extend approximately 90 degrees around the periphery of the plunger and being disposed in ofi,- set relation to the graduations 2|, 23, 25, 2l and 29. This gives approximately 180 degrees of the plunger surface on one side which is perfectly smooth and which can be turned to engage the detent I 9 when the syringe is being filled, When the syringe is lled, it will be turned until the detent I9 rests in the cavity 2l. Immediately after the needle is inserted in the patient, the plunger is turned to where the detent engages the smooth portion of the plunger immediately to the left of the cavity 2I in Figure 2, and the plunger is then, forced inwardly in the syringe barrel II) until the detent I9 falls into the cavity 22. For the next patient, the needle is inserted in the patient and the plunger is given a slight turn to the right of cavity 22 in Figure 2, or midway between the cavity 2I and 23 and the plunger is again forced inwardly and will automatically stop when the detent I9 falls` into the cavity 23. This operation is repeated until the plunger is moved all the way inwardly to where the detent I9 will rest in the cavity 30, at which time the last dose in the barrel is ready to be delivered.

It is thus seen that by graduating the plunger to deliver -any desired amount, and etching or otherwise forming these graduations in the form of cavities, and by use of the detent I9, it is therefore seen that a, definite amount of the fluid will be delivered into the patient upon each inward movement of the plunger, and the plunger will automatically stop when the detent I9 falls into the next succeeding cavity.

In the drawing and speciiication, there has been set forth a preferred embodiment of the invention, and although speciiic terms are employed,they are used in a generic and descriptive sense only, and not for purposes of limitation, the scope of the invention being defined in the claims.

I claim:

l. In a hypoderrnic syringe comprising a barrel portion and a plunger, said plunger having a plurality of graduations equally spaced thereon, said graduatio-ns being in the form of cavities extending for a portion of the periphery of the plunger, said plunger having a second series of gradua tions disposed on another portion thereof, and offset with relation to the first set of graduations, the second set of graduations also being in the form of cavities, said barrel portion having a spring-pressed detent mounted thereon adapted to engage the periphery of the plunger, and to fall into one of the graduations when the plunger is moved inwardly, the plunger being adapted to be rotated `axially to remove the detent from the cavity into which it has fallen so that as the plunger is moved further inwardly, the detent will fall into a cavity in the other set of graduations on the plunger.

2. In a hypodermic syringev having a barrel portion and a plunger, the plunger having a plurality oi graduatons extending for a portion of the periphery of the plunger, said graduations being in the form of cavities, said plunger having also, another set of graduations disposed on another portion of the plunger, and being in offset relation to the rst set of graduations, the second set of graduations being also in the form of cavities, and a spring-pressed detent mounted on the barrel portion of the syringe and adapted to press at allv times against the plunger to fall into one of one set of cavities when the plunger is in one position, and when the plunger is rotated relatively to the barrel, and moved further inwardly, the detent will fall into the next succeeding cavity of the second set of graduations.

. LOREN WALLIN. 

